The interest in RNAi remains unabated and might even be picking up steam. In this issue alone, we report on two RNAi deals: Roche investing in Alnylam while also buying its research center in Germany; and AstraZeneca penning a research collaboration with Silence Therapeutics to discover novel siRNA molecules in as many as five different therapeutic areas, with the possibility to expand the relationship at a later date. In all, these two deals alone could trigger more than $1.1 billion in payments for Alnylam and Silence which, coincidentally, is roughly the same amount that Merck ponied up late last year in its acquisition of Sirna.

There have been smaller deals over the past year in this space as well, but it's hard not to notice that roughly $2.5 billion has been committed to RNAi deals in less than a year by big pharma and this doesn't include whatever amounts these and other companies are devoting to this research area.

But is this money well spent?

To answer this, it might be helpful to look at the path to therapeutics taken by monoclonal antibodies, of which there are today more than 20 on the market treating everything from macular degeneration to cancer. The discovery of the method for producing monoclonal antibodies was invented by Kohler, Milstein and Jerne in 1975. Their Nobel Prize for this sizable contribution to medicine came nine years later in 1984. The first monoclonal antibody approved for use in the United States was another ten years down the road with subsequent monoclonal therapies coming afterwards in a steady stream.

Likewise, Craig Mello and Andrew Fire first published their RNAi paper in 1998 and received their Nobel eight years later in 2006. Despite some potential RNAi therapies currently moving through clinical trials, all appearances suggest that it could be at least another ten years before RNAi goldrush.

That's because, as Mello recently pointed out during his keynote address at DDT, there remain three challenges to broadly developing RNAi as therapeutics: stability, delivery and silencing efficiency. "We've made a lot of progress on two, so the real challenges are delivery, delivery, delivery," he said.

So why are companies throwing such large sums of today's dollars at something that might not pay off for more than a decade? Well, perhaps there was a lesson learned by some from monoclonal antibodies. As Lee Babiss, Roche's head of global pharma research, noted in his interview with Drug Discovery News: "Perhaps there are some companies which, 20 years ago, didn't make that investment in monoclonal antibodies and wished they had. This is a long-term investment and the delivery issue still needs to be solved. But we are confident that this problem will eventually be solved."

Some day, we may well look back at these huge bets on RNAi and shake our heads at how cheap, in a relative sense, these billions of dollars really were.